Ray Kurzweil incessantly dreams of the future. And it's a future he describes as a "human-machine civilization." In How To Create a Mind: The Secret of Human Thought Revealed, Kurzweil looks forward to a time when technology will have advanced to where it will be possible to gradually replace all the parts of the body and brain with nonbiological parts. And he claims that it will not change people's identities any more than the natural, gradual replacement of the cells in our body does now. All this will come about after scientists and engineers, who are currently working on brain models in many different organizations and areas of the world, succeed in creating a complete model of the human brain. Kurzweil contends that the neocortex functions hierarchically and that it works according to pattern recognition. Therefore, he argues, it is possible to write algorithms that will simulate how the brain actually works. That, in combination with increasing miniaturization, will make such substitution of nonbiological components possible by the 2030s.That the human brain is akin to a digital computer is still a big and a very contentious issue in neuroscience and cognitive psychology circles. In the January issue of Scientific American, Yale professor of psychology John Bargh summarizes some of the latest thinking about this problem. Specifically he addresses the major role of the unconscious in how people make decisions, how they behave in various situations, and how they perceive themselves and the world around them. There is a complex dynamic between ourcontrolled conscious thought processes and the unconscious, often automatic, processes of which we are not aware. Nobelist Daniel Kahneman explained this phenomenon in Thinking Fast and Slow. Automatic thought processes happen quickly and do not include planning or deliberation. Even Daniel Dennett, an eminent philosopher and cognitive scientist who has long held that neurons functioned as simple on-off switches that make them a logical switch similar to a digital bit, has recently changed his mind about the analogy of the human mind to a computer: "We're beginning to come to grips with the idea," he says in a recent Edge talk, "that your brain is not this well-organized hierarchical control system where everything is in order, . . . In fact, it's much more like anarchy. . . ." Yet even with this concession Dennett is still inclined to use the computer as a metaphor for the human brain. This leads him to make a curious statement, one which actually begs the question: "The vision of the brain as a computer, which I still champion, is changing so fast. The brain's a computer, but it's so different from any computer you're used to. It's not your desktop or your laptop at all." By his own admission, Dennett's talk is highly speculative: "I'd be thrilled if 20 percent of it was right." What I think he means is that the brain is like a computer that is far more complex than existing machines but that it also has intention. The neurons are "selfish," and they are more like agents than computer instructions, which in turn are more like slaves. "You don't have to worry about one part of your laptop going rogue and trying out something on its own that the rest of the system doesn't want to do." Computers, on the other hand, are made up of "mindless little robotic slave prisoners." So I'm not sure how helpful it is for Dennett to think of the brain as a computer at all. And Dennett's views on neurons and agents, combined with the more recent thinking about the impact of the unconscious on conscious thought, lead me to conclude that Ray Kurzweil's dream of someday replacing the human brain with robotic switches is just that: a dream.